Sensory evoked potentials (SEP) are being developed as tests of brain function, as a diagnostic tool to identify disfunction, and to elucidate neurophysiological processes in maturation and aging. Most recent studies involving SEP's are statistical, identifying distinctive SEP components with associated amplitudes and latencies and relating these measurable quantities to various subject samples. An approach that has not been fully exploited is the deterministic one of localizing and describing the neural generators of SEP components using scalp recorded potentials alone. We propose to develop mathematical models to infer the locus and configuration of the sources of such components and obtain as much information as possible from scalp recorded data by asking the appropriate mathematical questions. Among the advantages of this theoretical approach is its noninvasiveness, the possibility of replacing difficult neurophysiological questions by tractable mathematical ones, and the possibility that the models are predictive. Generally, the input data for these computer implemented models will be obtained from available studies and the models validated through extant clinical and empirical evidence. By adjusting the parameters in the models it should be possible to assess the effects of the geometry and conduction properties of the head on intracranial electrical fields and approximate such physical quantities as conductivity and conduction velocity and their changes in disorder, maturation, and aging. Finally, preliminary work has demonstrated that such a theoretical approach does correctly predict the locus of a source on an SEP component, indicating the usefulness of these methods.